The present invention relates generally to DC brushless electrical drives, and more specifically to controlling such electrical drives.
Improving the efficiency and technical characteristics in the control of electrical drives is of great importance in modern industry. Electrical drives of different types are ubiquitous in factories, laboratories, offices, in private homes, and in private and public transportation. Global production of electrical motors is estimated in several millions per day. Such enormous use of electrical motors underscores the need for effective control of electrical drives.
Control of electrical drives begins by determining the rotor position and speed. There are numerous information technologies and practical systems for controlling electromechanical devices, and specifically electrical motors of different construction. The basic differences between these systems stem from the chosen information parameter and corresponding sensor. First, the position of the rotor may be determined by an array of phototransistors and a special shutter coupled to the rotor shaft, or by using encoders, Hall-effect sensors, potentiometers, resolvers etc. Second, the speed signal may be obtained by using a small permanent magnet tachometer generator attached to the drive, or by using magnetic or optical sensors that generate pulses for each angular increment of the rotor. Third, a resolver may determine the position of the rotor by a two-phase (sine/cosine) signal at a carrier frequency that is modulated sinusoidally by the rotation of the rotor. However, all these methods have many disadvantages, such as the inability to determine the position of the rotor with high accuracy, the necessity to use different sensors with all auxiliary systems enabling their operation, the lack of a unified approach to the rotor position and speed determining, and the like.